Autoscroll: Bug or feature?

On my system (Windows 10), if the Interaction Pane (the docked right-hand panel) autoscrolls when you move the mouse up and down the area. This isn’t true for the Notes or Style Pane.

Is this deliberate or is it a bug?

If it’s a feature then it is really, really annoying. No other software application does this and for me it makes the Interaction Pane border on unusable a lot of the time.